This invention relates generally to bar and rod rolling mills, and is concerned in particular with the provision of a multi-line rolling system which is ideally suited for, although not limited to, the rolling of substantially continuous product lengths, for example continuously cast billets or series of discrete billets joined end to end as by welding.
Maximizing rolling mill efficiency by minimizing unproductive "down" time is a matter of vital concern to all mill operators. This concept becomes even more important when rolling a substantially continuous billet, for in this situation an interruption in the rolling schedule usually necessitates an immediate disruption of the upstream billet processing equipment, and an attendant scrapping of the billet length already on its way to the rolling line.
Rolling interruptions are commonly occasioned by the need to replace worn equipment such as work rolls, guides, etc. The use of multiple alternately usuable rolling lines has already been proposed, where it would be possible for worn equipment on one rolling line to be replaced while rolling continued on another rolling line. In this connection, see for example U.S. Pat. Nos. 1,514,179; 1,935,048; 3,382,697; 3,383,896 and 3,930,395. However, in these known arrangements the rolling lines are driven by their own separate power sources, reduction gearing, etc. Such arrangements are thus very costly because of the substantial capital investment required for duplicated drive equipment, and the building space needed to house the mill equipment.
Other arrangements have been proposed where multiple rolling lines are driven by a common power source. In this connection, see for example U.S. Pat. No. 3,391,562. Arrangements of this type are also unsatisfactory because the rolling lines are not independently operable. Thus, if one rolling line is taken out of service, the other rolling lines must also be stopped.
The present invention has as its general objective the provision of a novel and improved multi-line rolling system which not only obviates the above-mentioned problems, but in addition provides other significant advantages of considerable importance to the mill operator.
The rolling system of the present invention basically comprises a plurality of rolling positions aligned in the direction of rolling. Each rolling position has at least two sets or pairs of work rolls, one pair forming a first rolling line and the other pair forming a second rolling line. The work rolls and their respective bearing chocks may be supported either in one or several housing structures. A power source is associated with each rolling position. The power source is connected to the roll pairs of each rolling line by an intermediate drive means which includes a clutch means. The clutch means operates to selectively interrupt the drive connection between the power source and the roll pairs of either rolling line. This permits one rolling line to be stopped for maintenance purposes while the other rolling line continues to roll product received from an upstream feed line. A switching mechanism alternately directs product from the feed line to either of the rolling lines. As soon as the required maintenance has been completed on a given rolling line, it can be clutched into operation and thereafter run "empty" in readiness for immediate use as soon as the other rolling line is rendered inoperative.
The rolling lines may be closely spaced by employing a single housing structure for all of the roll pairs at a given rolling position. This offers certain advantages, including a conservation of valuable building space and the possibility of servicing both rolling lines with rapidly traversable crop shears and dividing shears.
Alternatively, the roll pairs may be supported in separate widely spaced housing structures, with the power sources and the intermediate drive means located between the rolling lines.
In all cases, however, the rolling lines are separated by appropriate safety enclosures which allow operating personnel to service a deactivated rolling line while the other rolling line is in operation.